1. Field of the Invention
The present invention relates to an adsorbent for an oral administration, and a pharmaceutical composition comprising the adsorbent for an oral administration. The adsorbent for an oral administration, according to the present invention, comprises a porous spherical carbonaceous substance having a pore volume within a specific scope, and exhibits an excellent adsorbability of harmful toxins in gastrointestinal tracts, despite a low adsorbability of useful components such as digestive enzymes in a body, when orally administered. Further, when the present adsorbent is administered to patients suffering from liver or renal diseases, a remarkable curative effect can be obtained.
2. Description of the Related Art
In patients with a lack of a renal function or a liver function, harmful toxic substances are accumulated or formed in bodies, such as blood, with a progress of a disorder of the organ functions, and thus, an encephalopathia occurs such as a disturbance of consciousness or uremia. There is a growing number of such patients from year to year, and therefore, a development of an organ-substitute apparatus or medicament having a function to remove toxic substances from bodies, in place of such defective organs, has become a serious problem. A method for removing toxic substances by a hemodialysis is prevalent as an artificial kidney at present. Nevertheless, the hemodialysis-based artificial kidney requires a special apparatus, and thus, a skilled specialist is required from a safely operating standpoint of view. Further, blood must be taken from a patient""s body, and thus, there are disadvantages in that patients must bear high physical, mental and economic burdens. Accordingly, hemodialysis is not satisfactory.
Recently, as a means of remedying the above disadvantages, an oral adsorbent which can be orally administered and cure a disorder of renal and liver functions has received considerable attention. Specifically, an adsorbent disclosed in Japanese Examined Patent Publication (Kokoku) No. 62-11611 [=U.S. Pat. No. 4,681,764] comprises a porous spherical carbonaceous substance having particular functional groups; has a high safety factor and is stable to a body; and has a useful selective adsorbability, that is, an excellent adsorbability of harmful substances in the presence of a bile acid in an intestine, and a low adsorbability of useful substances such as digestive enzymes in the intestine. For these reasons, the oral adsorbent is widely and clinically used for a patient suffering from a disorder of a liver or renal function, as an adsorbent having few side effects such as constipation.
The inventors of the present invention engaged in intensive research to develop an oral adsorbent having a more excellent selective adsorbability than the above-mentioned oral adsorbent comprising the porous spherical carbonaceous substance, and surprisingly found that a porous spherical carbonaceous substance having a pore volume within a special scope exhibits an excellent selective adsorbability, that is, an excellent adsorbability of xcex2-aminoisobutyric acid, which is a toxic substance in a renal disease, despite a low adsorbability of useful substances, for example, digestive enzymes, such as xcex1-amylase, less than that of the adsorbent disclosed in Japanese Examined Patent Publication (Kokoku) No. 62-11611. Further, the present inventors also found that the newly found porous spherical carbonaceous substance has few side effects such as constipation, and exhibits an excellent function as an oral medicament for treating a liver or renal disease.
The present invention is based on the above findings.
Accordingly, the object of the present invention is to provide an oral adsorbent exhibiting an excellent selective adsorbability.
Other objects and advantages of the present invention will be apparent from the following description.
In accordance with the present invention, there is provided an adsorbent for an oral administration, comprising a porous spherical carbonaceous substance wherein a diameter is 0.01 to 1 mm, a specific surface area determined by a BET method is 700 m2/g or more, a volume of pores having a pore diameter of 20 to 15000 nm is from not less than 0.04 mL/g to less than 0.10 mL/g, a total amount of acidic groups is 0.30 to 1.20 meq/g, and a total amount of basic groups is 0.20 to 1.00 meq/g.